Merge "Spec: Deploy Kolla images using Kubernetes"

specs/kubernetes-deployment.rst

+===================================
+Deploy Kolla images with Kubernetes
+===================================
+
+https://blueprints.launchpad.net/kolla/+spec/kolla-kubernetes
+
+Kubernetes was evaluated by the Kolla team in the first two months of the project
+and it was found to be problematic because it did not support net=host,
+pid=host, and --privileged features of docker.  Since then, it has developed
+these features. (https://github.com/kubernetes/kubernetes/releases/tag/v1.2.0)
+
+Though Kolla deploys the containers using Ansible, we can leverage the current
+work by using the config generation and injecting the configs into
+the Kubernetes pod.
+
+
+Problem description
+===================
+
+Kubernetes
+- life-cycle management: service monitoring, restarting, and scaling
+- upgrades: rolling and all at once upgrades
+
+Kubernetes has services/tools that can provide service monitoring, health
+checks, service scaling, and upgrades.
+
+We can use the scheduler to assign work loads to appropriate nodes.
+Kubernetes has built in health checks that will maintain the container's status.
+And we can use the replication processes[1] to scale up and down our stack.
+
+For upgrades, Kubernetes has a tool called 'deployments'[2], which will
+detect when there is a config change in the container and start scaling
+down the current running container and scaling up the new container. If
+the new container fails, it can roll back, a nice feature containers provide
+for us.  Though this is oversimplified for OpenStack, we can make use of this.
+
+
+Proposed change
+===============
+
+- Add a deployment specific git repo (kolla-kubernetes) to contain the
+  Kubernetes deployment code.
+
+Bootstrapping
+-------------
+
+Kubernetes provides RestartPolicy which allows to define whether a container
+should be restarted and when[3]. It may be used for bootstraping.
+
+Another alternative is Ansible, which runs a number of scripts to setup the
+database, keystone, etc..
+
+Security impact
+---------------
+
+The deployed OpenStack’s security should not be affected by the deployment tool.
+In addition, if we containerize the config data so that it can be injected into
+a pod, we can leverage the selinux capabilities in the config container.
+
+Performance Impact
+------------------
+
+Unknown
+
+
+Implementation
+==============
+
+Primary Assignee(s)
+-----------
+  Ryan Hallisey (rhallisey)
+
+Other contributor(s):
+  Michal Rostecki (mrostecki)
+  Swapnil Kulkarni (coolsvap)
+  MD NADEEM (mail2nadeem92)
+  Vikram Hosakote (vhosakot)
+  <Please add your name here if you are getting involved in kolla-kubernetes>
+
+Milestones
+----------
+
+Target Milestone for completion:
+  unknown
+
+Work Items
+----------
+1. Change start.yml files so that they can inject configs into Kubernetes pod.
+2. Add support for kolla-kubernetes to kolla-cli.
+
+
+Testing
+=======
+
+Functional tests will be implemented in the OpenStack check/gating system to
+automatically checks that the Kubernetes deployment works for an AIO
+environment.
+
+
+Documentation Impact
+====================
+Add a quick start guide which will explain how to deploy kolla-kubernetes.
+Add a develop guide on how to contribute, which also explains how the
+deployment works.
+
+
+References
+==========
+
+- [1] http://kubernetes.io/v1.0/docs/user-guide/managing-deployments.html
+- [2] https://cloud.google.com/container-engine/docs/replicationcontrollers/
+- [3] https://github.com/kubernetes/kubernetes/blob/master/docs/user-guide/pod-states.md#restartpolicy
+- https://github.com/kubernetes/kubernetes